The pathogenesis, molecular biology, immunology, natural history, and therapy of human herpes virus infections are being investigated. Immunocompetent and immunodeficient patients with a wide range of herpes virus infections have been identified, followed clinically, diagnosed by virus isolation, studied immunologically, and, in some cases, treated successfully with systemic antiviral chemotherapy. Our major focus on the study of molecular biology and latency of varicella zoster virus DNA has continued. During the past year we have completed studies on the restriction endonuclease analysis and molecular epidemiology of varicella zoster virus DNA. We have molecularly cloned a library of varicella zoster DNA fragments, and have nearly completed physical mapping of varicella zoster virus genome.